Taylor Swift continued her parade of incredible guest stars — which has included Ed Sheeran and Sam Smith — for her third of five nights at London’s O2 Arena. Danny O’Donoghue, lead singer of The Script, joined Taylor on stage in front of a sold-out crowd of over 15,500 to perform the band’s breakthrough single “Breakeven”!

Taylor introduced O’Donoghue by recounting her first time hearing the Irish rock band on one of her first trips touring in the UK, back when she was around 18, and before they’d even made it big in America! She complimented the band for its “incredible songwriting, unbelievable songs, and,” she teased, moments before revealing O’Donoghue was there to an excited roar from the crowd, “they have a really great lead singer.”

After the show, Taylor tweeted about the performance with her surprise guest: “The crowd went absolutely insane!” You can see just what she’s talking about by watching their duet in the video below now: